1. Technical Field
The present invention relates to a sheet discharging apparatus of a printer, and more particularly, to a sheet discharging apparatus that permits ink printed on the sheet to dry by delaying stacking the discharged printed sheet.
2. Related Art
In a general ink-jet printer, sheets of printed paper are discharged and then constantly stacked on a tray. As a printing speed of an ink-jet printer has increased, a speed of stacking discharged sheets of printed paper on a tray has increased. The increased speed of stacking causes the printed sheet to be stacked on the tray before ink on a previously printed sheet is dried. Therefore, ink printed on a sheet of lower-stacked paper is smeared over a back of upper-stacked paper.
In order to solve the above problem, there has been a known printer which delays stacking the discharged sheet. U.S. Pat. No. 4,794,859 discloses an active paper drop for printers which has a pair of opposed, movable rail members associated with opposed walls of a horizontal-disposed output collection tray for receiving sheets of printed media. Each rail member has a return spring that act to maintain the rails in a closed position. In that position, the rails support a sheet of the print medium during the printing operation, thus giving the ink on the previously printed-on sheet time to dry. The rails are provided with a wing member and are pivotally secured in the floor of the output tray, with the pivot point spaced inwardly from the wing member. Downward pressure against the wing member thus causes the rail to rotate outward from its closed position, into a recess formed in the side of the output tray. This provides sufficient clearance for the sheet to drop into the output stack. Upon release of the downward pressure, the spring causes the rail member to return to its original closed position.
According to the conventional sheet discharging apparatus, however, since the holders pivot upwardly and downwardly without a variation in a distance between the holders, printing media such as a post card having a smaller width than a distance between the pair of holders cannot be supported. Therefore, when the printing media having the smaller width is sequentially printed, the conventional sheet discharging apparatus cannot solve the above problem.
In addition to that, the holders in the conventional sheet discharging apparatus are exposed from the vertical wall of the tray when the printer stands by for printing a sheet. Therefore, there is a problem of that the holders are damaged by an external shock.
It is therefore an object of the present invention to provide an improved printer.
It is another object to provide for an improved sheet discharging apparatus.
It is further an object to provide a sheet discharging apparatus capable of supporting printing media of various widths by adjusting a distance between holders.
It is a still further object to provide a sheet discharging apparatus in which the holders are not exposed to an external shock when the printer stands by for printing a sheet.
It is yet a further object to provide a sheet discharging apparatus that allows a size of the printer body to be reduced.
The discharging apparatus having features of the present invention may be constructed with a tray on which printed sheet is stacked, a holder supporting said printed sheet above said tray, and a moving means for moving said holder in a direction perpendicular to a sheet discharging direction.
The moving means includes a motor, a rack reciprocating in a direction perpendicular to a sheet discharging direction according to the driving of the motor, and a pinion connected to an end of a rotary shaft of the motor and engaged with the rack. The holder horizontally moves above the tray in association with a movement of the rack.
The holder and the rack are connected to each other through a lever which pivots in the sheet discharging direction in association with the movement of the rack. At an end of the lever is mounted a driven gear engaged with the rack, and at the other end of the lever is formed a protrusion inserted into a guide slot which is formed in the holder.
It is preferable that a spring is interposed between the holder and the lever for biasing the lever to pivot toward the sheet discharging direction.
According to the sheet discharging apparatus as constructed above, the holder horizontally moves above the tray, thereby supporting printing media of various widths above the tray.